Sound recording apparatus



Feb. 20, 1945. Q REEVES 2,369,916

SOUND RECORDING APPARATUS v Filed Sept. 14, 1942 2 Sheets-Sheet lINVENTOR A077 5 A res $53M ATTORNEY A. E. REEVES SOUND RECORDINGAPPARATUS Filed Sept. 14, 1942 2 Sheets-Sheet 2 Ema- INVENTOR 4/761/1 5Faves BY ATTORNEY Patented Feb. 20, 1945 TED sures PATENT omcsl v scum)233; arrm'rus it nflleizl sztfixirrg e No. assess 12 Claims.- ('01.179-4003) by providing a unitary glow tubestructure that is capable ofproducing both complementary glows; Thus for ex This invention relatesto sound recording apparatua'and more particularly to apparatusthatutilizes a glow tube.

This applicationls a continuation in part of an application filedJanuary 16, 1939, in the nameof Arthur E. Reeves, under Serial Number251,155,

and entitled "Glow tube," and patented on November 3, 1942, No.2,300,809.

'Glow tubes or the character, illustrated in said prior application arealso described and claimed in Patent No. 2,270,967, granted January27,1942, to Arthur E. Reeves, for a glow tube. 4

Such glow tubes in general include spaced electrodes between which aglow or actinic radiations are produced, the intensity ofwhich is variedin accordance with the impulses to be recorded.

This varying illumination is caused'to aflect asensitizedvfilm that 'ismoved past the glow. In

this way, a, variable density sound track is pro- .duced.

In the forms of glow tubes described in said prior application and priorpatent, the electrodes between which the glow is produced are flat,closely spaced plates, and the space between the plates is presentededgewise to the sensitized surface. By appropriate insulation supports,the glow is confined between the opposed electrode surfaces. I

It has been proposed in the' past to produce two cooperating push-pullsound tracks for recordin the impulses. Such sound tracks arecharacterized bythe fact that one is the complement of the other;therefore as the density of one component track varies longitudinally ofthe two tracks,

the density of the other component varies in the opposite direction. Theadvantages of such a push-pull arrangement are now well-understood, bothforrecording and reproduction. I v

The electrical impulses that are to be recorded are almost invariablyamplified before they serve to modulate the intensity'of illumination orslow 1 produced by the glow tube. Accordingly when a push-pull type oftrack is to be recorded.-. is necessary to use amplifier stagesl1keW1Segl'-. ranged in push -pull relation. For optimum results, theamplifier stages must be balanced, and

7 the glow tubes that produce the varying light intensities must alsohave identical characteristics. These ideal conditions are, difficult toapproximate in systems operating in accordance with the Prior art.

It is one-of the objects of this invention to I This object isaccomplished ample, the glow tube may have a common anode, large enoughsimultaneously to cooperate with a pair'or cathodes. -.'I'lie-glowbetween the anode v and each of the cathodes affects separateportions-or the sensitized photographic film. The balancing of the twotracks involves careful consideration to the dimensional-accuracy of theelectrodes and their spacing. By placing both cathodes; in the sameenvelope, both glows exist under identical fluid pressure conditions.

In the event separate glow tubes were utilized to obtain the glows forrecording the complementary tracks, these tubes would have to be chosenby trial and error, until a pair be found having closely matchingcharacteristics. Since most tubes are filled with a mixture of inertgases at low pressures, any variation-for examplein the It isaccordingly another object of this invention to provide a'unitary glowtube structure for push-pull recording, in which the glow-effects areproduced in a common envelope.

In the prior application hereinabove identified,

a lens system is described and claimed for deter- A mining the finaldimensions of the image of the make it possible easily to balance theglow tube eiiects, and thereby to approach the ideal condi tions foraccurate push-pull recording. a

,glow that is focused upon the sensitized photographic surface. In thisway, the full glow can be utilized, and the necessity of usingmechanical slits is obviated. It is another object of this invention toadapt the push-pull tube structure for cooperation with alens system ofthis character. Thisinventionpossesses many other advantages, and hasother objects which may be made more easily apparent from aconsideration of one embodiment of the invention. For this purpose thereis shown a. form in the drawings accompanying and forming part of thepresent specification. This form will now be described in detail,illustrating the general principles of the invention; but it is to beunderstood that jthil detailed description is not to be taken in alimiting sense, sincethe scope of. this invention is best defined by theappended claims.

Referring to the drawings:

Figure 1 is a view, mainly in longitudinal section, illustrating anapparatus incorporating the invention:

'2-2 of P18. 1'; Fi 3 is an end-view of the lens barrel ut in.connection with the invention, and viewed from plane 3-4 of Fig. 1;

4 is an end view of the lens barrel taken from the right of Fig. 1; Fig.5 is a fragmentary sectional view, taken 'along plane 5-! of Fig. 1;

Fig. 6 is a. sectional view, taken along plane 6-6 of Fig. 5;

Fig. 'I is a fragmentary plan of a push-pull sound track produced by theaid of the inven tion; and

Fig. 8 is a wiring diagram of an electric recording system incorporatingthe invention.

The glow tube structure includes a sealed transparent envelope orcontainer I (Figs. 1 and 2), having a rounded end. In the presentinstance this envelope is-shown as telescoped within a tubular mounting2. In one end of mounting 2 there is an aperture 3 through which thelight radiations produced within'the tube are passed to alens systemprovided in a lens barrel 4. The manner in which the lens barrel issupported will be hereinafter described. It is suflicient for the momentto point out that the lens system serves to focus the images of the glowdischarge upon a suitable sensitized surface.

- The envelope 1 may be held within the mount 2 in any suitable manner;for example, the base 5 of the glow tube may carry a split ring Thisring is tightly clamped as by the aid of the screw 7 upon the base 5.Rods 8 are carried by the enlarged flange 9 of the mount 2. They passthrough appropriate apertures ill in the ring 8. A thumb screw H isthreaded into the ring 6. and

has a iiange 12 which clamps against one of the Y rods 8.

The lens barrel 4 is shown as having aiiange 13. This flange i3 isguided for axial movement by the aid of the guide pin I4 fastened in themount 2. This pin I4 is engaged in a guiding aperture 15 formed in theflange 13. The barrel 4 is urged resiliently toward the right, as by theaid of a compression spring l8 disposed between the end wall or themount 2 and the flange l3.

The lens system maybe adjusted axially for the purpose of focusing bythe aid or a focusing sleeve 11. This focusing sleeve has a running fitwith respect to the barrel 4 and engages the right trode structureformed of sheet metal, and sup- P rted in a massive block of insulation2|. This block of insulation 2! is shown as appropriately grooved sothat the upper surface'22 of'the block 2| is coincident withtheupper-surface of the electrode structure. 2|. made of lavite.

Juxtaposed to the active upper surface of the The block 2| may be.electrode 20 are the two electrodes 22 and 24.

These two electrodes are also made of appropriate sheetmetal and aresupported by an insulation block 25, similar to block 2|. The activesurfaces of electrodes 23 and 24 are portions of a con-- tinuous plane,and ar placed closely adjacent to each other. These electrode surfacescooperate with different portions of the electrode 20, which has anactive upper surface coextensive with the combined active surfaces ofelectrodes 28 and 26.

In order to hold the electrode structure in proper assembled relation,each of the blocks 2| and 25 is provided with a side flange 26 or 21respectively. These flanges as shown most clearly in Fig.

6, contact the adjacent surface of the opposite block 2| or 25, to forma rectangular narrow openingor space 28 between the electrodes. Further!more, in order to ensure against sputtered metal (that may be depositedupon the insulation blocks 2| and 25) from bridging the electrodes, the

r space '28 between the electrodes kept open as hand surface of flange13. It is also provided with an externally threaded extension I. adapted to be in threaded engagement with the tubulaiextension I! formed onthe mount 2.. The inner cylindrical surface of extension 18 has arunning fit with the flange l3. Accordingly if it is desired to move thebarrel 4 toward the left as viewed in Fig. 1, the: sleeve II ismanipulated so as to turn the extension I8 inwardly with re spect to theextension I9, thereby further coinexpand and to urge the flange itagainst the end wall of focusing sleeve I'l.

As explained in theprior patent hereinabove referred to. electrodes aresupported within the envelope I, which, when supplied withsuitableelectrical potentials, form a glow that may be modulated inaccordance with the sound impulses to be recorded. These electrodes areshown m st much-as possible on all sides. For this reason the sideflanges 26 and .21 are slotted as indicated by the slot 29 in Fig. 1.All this is shown and described in the said prior patent hereinbeiorereferred to.

The insulation blocks 25 and 26 with the electrodes 20, 23 and 24 areheld in assembled reiation by the aid of the bolts 30 which pass throughthe side portions of the insulation blocks 2i and 25.

The electrical connections for the electrodes 20, 23 and 24 are providedby conductors 3H, 32 and 33. These conductors are made quite large indiameter, to serve as well as supports which pass through the press 34of the evacuated con= tainer I. These conductors terminate in prongssuch as 35, 36, supported at the end of the base and adapted tocooperate in a well-known manher with a suitable receptacle. In order tolend further rigidity to ,the support, of the electrode structure uponthe press 34, an additional metallic support 3'! (Fig. 2') similar tothe conductors 3|, 32 and 33 is joined to the common electrode 20 and isimbedded in thepress 34.

The circuit arrangements are such that two glow discharges arejformed:one between the electrode 20 and electrode 28; and another betweenelectrode 20 and electrode 24. The space discharges between theseelectrodes are so modulated that they are in push-pull-- relationship.For this purpose the electrode 20 for example, can be an anode, andelectrodes 23 and 25 can be cathodes. They are so indicated in thediagram of Fig. 8. Inthis diagram, electrode 20 is shown asconnectedtothe positive terminal of a source of direct'lcurrentenergy, such as thebattery 38. The negative terminal of the battery is ccnnectedto thecentral trip of the secondary coil 38 of the'transi'ormerll. Theterminals of the secondary coil 30 are connected respectively to thecathodes 23 and 24. v

The primary coil 4! is connected to the output oiampliiiersystem 42.This amplifier sysclearly in Figs. 5. and 6. Thus there is an elect-1tom serves to amplify sound impulsesied to the input of the system 42 asby the aid of a microphone 43.

Assuming that there are no signaling impulses flowing in the circuitassociated with the microphone 43,. a glow .of intermediate intensity iscaused to be produced between each of the electrodes 23, 24 and theanode 20. Such an intermediate glow may be determined by proper choiceof batteryv potential, whichis made efiective across the electrodes.

When a signaling impulse is transmitted, an electromotive force isinduced inthe secondary coil 39. If we assume that the impulse is insuch a direction as to make the upper terminal of coil iii! positive,then the potential ofelectrode 24 ismade more positiv than before, andthe potential of the other electrode 23 is made less posi- .tive. Theglow between cathode 24 and anode is accordingly reduced, because thepotential difference between these two electrodes is reduced. At thesame time, the glow between electrode 23' and anode 20 is increased..Upon a change in sign of the impulses, the glow increases betweencathode 23 and anode 20. Since the impulses to be recorded are passed tothe glow tube circuit through a transformer such as 40, the potentialsacross the coil 39 change in sign in accordance with the impulses in themicrophone circuit.

The production of a glow discharge between the electrodes byappropriatechoice of potential difierences is readily obtained, especially when thepressure and character of the gaseous filling in the envelope I aresuitably chosen. The gaseous filling in the envelope I is usually amixture of inert'gases, such as a mixture of several of the noblemonatomic gases.

'7) 'upon which the sound tracks 44 and 45 are to be photographed, isfed past the lens system at a uniform rate. Tracks 44 and 45 are of sucha naturethat a dark portion along one track is opposite a light portionon the other track, thus conforming to the push-pull pattern.

In view of thefact that both of v charges occur in a common evacuatedenvelope l (which encloses all of the electrodes and their supports), itis a simple matter to balance the glow discharges so that theysubstantially accurately correspond to the ideal push-pull requirements.

Furthermore, in order to ensure that the illumination of one glowdischarge will not interfere with that of the other, separating shieldsin the formfof septaare provided. For example, a semi-circular hield orseptum 50 (Figs. 1, 2 and 5) may be supported upon insulation blocks 2|and 25, and having its main plane disposed between the two glows. Thisplate 50 may be made of refractory material such as thin mica. It may beprovided with a slot 5| to permit it to be passed over the outersurfaces of the blocks 2| and 25. It may be held in place upon theblocks by the aid of the bolts 55 that pass through oppositely directedprojections 52 and 53. These projections are formed integrally with theblocks 2| and 25. 1

-A corresponding septum 54 is carried by the lens barrel 4 and isdisposed ,between the two lenses 46 and 41. This septum ,may be of thinmetal, such as copper, anchored in the anchor pins 56. These anchor pins56 may be supported I in the flange l3 of the lens barrel 4.

The two discharges, respectively between an- I ode 20 and cathode 24 andbetween the anode 20 and cathode 23, are presented edgewise to the lens-Fig.' 3, a pair of cylindrical lenses 46 and 41 is illustrated as beingdisposed respectively to receive the illumination of the glow dischargesformed between electrodes 20 and 23, and between electrodes 20 and 24.These cylindrical lenses 46 and 41 have vertical axes. Accordingly theyserve to reduce the width of the glow image, in a horizontal direction.Asshown most clearly in Fig. 3, these lenses are set closely together,

to correspond to the spacing of the electrodes- 23, 24. Accordingly itmay be necessary to cut away the'adiacent edges 'of these lenses; butthis has no appreciable effect upon the optical properties of thelenses. J I

Similar cylindrical lenses 48 (Fig. 4) are disposed with horizontalaxes, within the barrel -4, to reduce the-thickness orjverticaldimension of the image of the glow. These lenses are exposed at theright hand end, of the barrel 4. The

ultimate dimensions of the glow images are made to conform to suitablevalues, without masking out any of the glow. Intenselyluminous imagescan thus beproducedmnd there is a corresponding improvement in thefaithfulness of the record.

The photographiefllm or phonofllm 48 (Fig.

The septa 50 and 54 are arranged to cooperate with each other by virtueof the guiding rods 8 and the guide pin l4, in such manner that the mainplanes of these septa are coincident. Cross illumination from thepath-of one glow discharge to the path of the other is thussubstantially entirely prevented by the septa.

What is claimed is:

' 1. In combination, a pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces forming portionsof a continuous surface, a common electrode structure. having a,discharge surface substantially coextensive with the said flrstdischargesurfaces and spaced therefrom so as to cooperate therewith and to form apair of space discharge paths, and

. a common sealed envelope for all of said electrodes. v

2. In combination, a pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces forming portionsof a continuous surface, a common electrode structure having a dischargesurface substantially coextensive with the said first discharge surfacesand spaced therefrom so as to cooperate therewith and to form a pair ofspace discharge paths, means for shielding the illumination of the glowdischarges from each other, and a common sealed envelope for all saidelectrodes and said shielding means.

' 3. In combinations. pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces-forming portionsof a con- 'tinuous surface, a common electrode structure having adischarge surface substantially coextensive with the said firstdischarge surfaces and spaced therefrom so as to cooperate therewith andto form a pair of space discharge paths, a

common sealed envelope for all of said electrodes,

and a pair of lens systems to which the discharge spaces are-presentedin edgewise fashion.- a

the glow disthe film. e1

ture having a disc by side,

4. In combination, a pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces formingportionsof a continuous surface, a'common electrode structure having a dischargesurface substantially coextensive with the said first discharge surfacesand spaced therefrom so as to cooperate therewith more charge surfacesand cooperate therewith and to form a pair of space and to form a pairof space discharge paths, a

common sealed envelope for all of said electrodes, each of said lenssystems being arranged to provide an image of substantially the entireglow that is associated with the respective system, said image havingdimensions suitable to be focused upon a sensitized photographicsurface.

5. In combination, apair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces forming portionsof a condischarge paths, insulation supports ;for the electrodes and theelectrode structure, said supports covering substantially all of theelectrodes but the active electrode surfaces, and a septum carried bysaid supports for segregating the illumination from the space dischargepaths from each other, and a common sealed envelope tinuous surface, acommon electrode structure having a discharge surface substantiallycoextensive with the said first discharge surfaces and spaced therefromso as to cooperate therewith and to form a pair of space dischargepaths, a common sealed envelope for all of said electrodes,

a pair of lens systems to which the discharge spaces are presented inedgewise fashion, and means for shielding the illumination of the glowdischarges from each other.

' 6. In, combination, a plurality of electrodes, a sealed containerforming a common space for the electrodes, said electrodes forming pairsof opposed electrode surfaces, said pairs being subfor segregating theillumination fro stantially identical, to provide a pair of space disesurface substantially cosaid first discharge surfaces of spacedischargepaths. a common sealed envelope for all of said electrodes,- and apush-pull am its out t connected to said electrodes to producecomplementary glows across said paths.- 8. Incombination. a pair ofsubstantially equal, electrodes having discharge surfaces isposed sidesaid forming portions of a continuous surface, having adlscha tenaivewith the ry glows at spaced areas of plifler system having for all ofsaid electrodes, said supports and said septum.

' 10. In combination, a pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces forming portionsof a continuous surface, a, common electrode structure having adischarge surface substantially coextensive with the said firstdischarge surfaces and spaced therefrom so as to cooperate therewith andto form a pair of space discharge paths, a pair of insulation blocks forrespectively supporting said common electrode structure and the pair ofelectrodes, each of said insulation blocks covering substantially all ofthe respective electrode areas but the active surfaces, and said blockseach having a projection -extending away from the active surfaces, and aseptum supported by the aid of said projections in the space dischargepaths from each other.

11. In combination, a pair of substantially equal electrodes havingdischarge surfaces disposed side by side, said surfaces forming portionsof a continuous surface, a common elecc, said surfaces forming portionsof a e,- a common electrode strucom so as to'cooperatethereaubeliminating. th

trode structure having a discharge surface sub-- -stantially coextensivewith the said first dis- :charge surfaces and spacedtherefrom-so as tocooperate therewith and to form a pair of space discharge paths, a pairof insulation blocks for respectively supporting said commonelectrodestructure and the pair of electrodes, each of said insulationblocks covering substantially allof the respective electrode areas butthe active surfaces, and said blocks each having a projection extendingaway from the active surfaces, and a septum supported by the aid of.said projections for segregating the illumination from the spacedischarge paths from-each other, each of said blocks having an integralspacer adjacent an edge thereof, and adapted to cooperate with theadjacent edge of the 0th blocks in spaced relation.

12. In, apparatus for the production of a f-phonofllm having a glowdischarge tube as the source of light and electrical means formodulating the glow in correspondence with sound variations;characterized in that the glow tube comprises a pair of sets ofelectrodes, each set having closely. spaced surfaces, sound modulatedglows being produced in, push-pull relations between the two sets ofelectrodes, the

v thetube,andapair respectively-interposed between the glows and thefllmand subtendlng respectively the en same to suitable e use of-slits andthe like.

E. REEVES.

spaced therefrom so as to or block, to hold said tire sectional area ofthe glows and I ons for sound records

